In a radio communication system, such as a wireless Local Area Network (LAN) system and a digital cellular communication system, a plurality of radio stations share a predetermined frequency band in performing communication. Consequently, in such a system, a radio station on the receiving end (i.e., reception station) not only receives a desired signal, which is a signal addressed and transmitted to the reception station by a radio station with which the reception station is performing communication (i.e., transmission station), but also receives an interfering signal, which is a signal transmitted by a radio station that is unrelated to the communication performed by the reception station (i.e., interfering station).
When a transmission period over which the transmission station transmits the desired signal overlaps a transmission period over which the interfering station transmits the interfering signal, the reception station receives the desired signal with the interfering signal superimposed thereon in the overlapped period.
Assume the above case where the reception station receives the desired signal with the interfering signal superimposed thereon. Here, for example, if a received power of the interfering signal is larger than a received power of the desired signal on the reception station side, or if the desired signal and the interfering signal were transmitted using the same channel frequency, then the interfering signal renders errors more likely to occur in demodulating the desired signal.
In light of the above, there have been provided interference suppression technologies for, when an interfering signal is superimposed on a desired signal, suppressing the superimposed interfering signal in accordance with a characteristic amount of the interfering signal, so as to prevent errors in demodulating the desired signal.
One of the conventional interference suppression technologies regards a desired signal as a wideband signal and an interfering signal as a narrowband signal that is transmitted periodically (for example, see Patent Document 1).
The above interference suppression technology judges that a received signal is an interfering signal if a received power of the received signal changes in constant cycles, and estimates a characteristic amount of the interfering signal. This way, when a signal that includes a desired signal is received, the above interference suppression technology suppresses the interfering signal that has been superimposed on the desired signal included in the received signal, by using the assumed characteristic amount of the interfering signal.
Patent Document 1:
Japanese Laid-Open Patent Application No. 2002-374179